The horse's foot and its sixth sense

Image courtesy of Equine Hoof Explorer

The sensory structures within the horse’s hoof, and the way they are used, are often under appreciated.

The horse’s foot has both pain receptors and touch receptors which gives it the ability to perceive the environment. Most of the nerves within the horse’s lower limbs are sensory nerves filled with neurotransmitters. Receptors in the horse’s foot use these transmitters to send information to the spinal cord and the brain.

Proprioception is what allows the horses limbs to move into the right position, with the right speed and the right amount of force required for the activity.

This “sixth sense” allows the horse to traverse a variety of surfaces without injury. Proprioception is aided by the Pacinian corpuscles which are located in the foot – many in the heel bulbs and the frog spine.¹

Horses (and many other animals) can detect a wide range of frequency vibrations through the Pacinian corpuscles in their feet. They can detect approaching animals and floodwaters.

Horses have been known to feel the vibrations through their feet several days before an earthquake when living on fault lines and research has shown that elephants not only “hear” but communicate through their feet.²

As there are no vibration sensory receptors in the toe – they are all in the frog and heels - horses should land heel first in all gaits.

The horse’s veins return blood back to the heart and body by pulsating and activation of the sensory receptors from various surfaces will influence the blood flow through the foot. Because the horse’s hoof is a neurosensory organ, when one foot is stimulated, the sensory nerves will affect change in the opposite foot.

Research was conducted by immersing one foot in ice with blood flow being measured in both the right and left foot. In the “iced” foot the blood vessels constricted and the blood slowed immediately as the hoof wall dropped in temperature. However, the opposite foot also recorded a constriction of blood vessels and a slowing of blood flow even with the hoof wall temperature remaining unchanged. This is assumed to be due to the sensory nerves conveying that information to the spinal cord and to the opposite limb.³

The same research also showed that standing on different surfaces will affect the flow of blood through the horse’s hoof and, consequently, the health of the horse’s foot. When a horse was standing on concrete the blood decreased dramatically, however, when a cotton washcloth was placed between the concrete and the hoof, blood flow returned to normal.

Small, rounded gravel is an excellent surface for the horse to stand and walk on as it is conformable, supportive and stimulates normal blood flow.